Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
typedef long long int uli;
string b[55];
int d[55][55];
int dir[4][2]={{-1,0},{0,1},{1,0},{0,-1}};

int main(){
  int n,m;
  scanf("%d %d",&n,&m);
  int black=0;
  for(int i=0;i<n;i++){
    cin>>b[i];
    for(int j=0;j<m;j++)black+=(b[i][j]=='#');
  }
  if(b[0][0]=='#' || b[n-1][m-1]=='#'){
    puts("-1");
    return 0;
  }
  queue<pair<int,int> >q;
  memset(d,-1,sizeof d);
  q.push({0,0});
  d[0][0]=0;
  while(!q.empty()){
    int r=q.front().first;
    int c=q.front().second;
    q.pop();
    for(int i=0;i<4;i++){
      int nr=r+dir[i][0];
      int nc=c+dir[i][1];
      if(0<=nr && nr<n && 0<=nc && nc<m && d[nr][nc]==-1 && b[nr][nc]=='.'){
        d[nr][nc]=1+d[r][c];
        q.push({nr,nc});
      }
    }    
  }
  if(d[n-1][m-1]==-1){
    puts("-1");
    return 0;
  }
  printf("%d\n",n*m-black-d[n-1][m-1]-1);
  return 0;
}